All plow anchors did poorly in mud after 6 minutes

Brian,
Have you ever tried a hinge point closer to the fluke tip?
Does Fortress even do R&D?

I dislike using wind only as a test of an anchor.

Most wreckage I have seen after storms were from surge and possibly sailing atound the anchor.

Even Phil Bolger in one of his books I believe discusses that often sailboats drag while right next to larger wind profile power vessels.

Both he and I seem to think that watching sailboats in a unprotected anchorage from large rollers really hobby horse and sail around compared to their power bretheren

I have also seen vessels just slightly more exposed than othere of the same type that drag.

Same winds yet more water action.

Thus I am suspect of anchors that are rated in tests that use steady even pulls....and possibly even the "technique" of anchoring and total ground tackle.

I believe anchoring is like learning anything in heavy weather. The only sure fire experience is by gradually testing in worse and worse conditions till it is just too dangerous...then extrapolating to known survival methods.

Even though the USCG pilots that successfully save people in horrible conditions, training minimums are lower...like basic technique establishment. The real test comes from years of experience in pushing the envelope further and further.

Till you do thst...everything is really just a guess.

Nomad Willy said:

Shrew,
Good point.
But the method Fortress used did IMO show what the anchors could do anchoring in slimy mud. No anchor test will duplicate your next anchoring scenario. And no anchor test is free of all the troublesome variables. Lots of anchor tests can be very misleading I admit. The one that takes the cake (as they say and IMO) is the Mantus vidio of someone pulling a Rocna over a hard sand beach at the perfect angle so it only skids along. And Rocna did a similar one pulling a CQR over a dry beach at high speed. Pulling anchors in sand boxes at boat shows or (to a lesser degree IMO) dragging anchors on beaches at low tide not even in the water is lacking of real world anchoring but they all "indicate" what an anchor may do in the real world. Steve on Panope came about as close to real world as one can get but his tests were'nt really representing typical anchoring .. more like worst case scenario in a specific way (tide reversals). Steve was going up north last I heard.

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Eric, during the Chesapeake Bay testing, every anchor was pulled 100-ft for 10 minutes (10-ft per minute), and that pull speed was recommended by our consultant Bob Taylor, a retired US Navy anchor design and soil mechanics expert with over 45 years in the field. Obviously, the anchors were pulled slow enough and given sufficient distance and time to perform, or not.

Regarding beach testing, which from what I have seen is usually conducted on brick hard sand, it definitely has a value IF that is where you plan on anchoring.

Nomad Willy said:

Brian,
Have you ever tried a hinge point closer to the fluke tip?
Does Fortress even do R&D?

Click to expand...

Eric, I am not aware of us ever trying to put the hinge point closer to the fluke tip. We have several original prototypes here and I have not seen that design type.

We did extensive R & D during the lead up to our initial production, and we continued to make product modifications afterwards during the first several years as well. We have numerous images of our late founder testing anchors in the nearby muddy swamps of the Florida Everglades and off the local Florida shoreline where he conducted sand bottom testing.

Additionally, we have a structural test machine called "Black Maria" which tests loading points on an anchor during typical pull conditions.

Fortress anchors have had ABS certifications since the early 90s, and the performance and survival of three anchor models during the 1989 US Navy tests was a mission critical point during the launch of our product.

"You go up one size .....
From what? What the manufacturer recomends?"

Not really , I think most mfg recommendation is based on what price they think will not be too high for that type of vessel.

Skenes perhaps and other sources will give the wind pull loading at various wind speeds.

Usually its not very much for a boat that does not sail its anchor. Surge loading is brutal.

The unsteady boats simply need to bite the bullet and deploy a second bow anchor every time!.

Not a big deal and makes the boat steady, and the rest of the harbor happy..

My anchor collection for our 50ft lobster boat style launch is almost all Danforth H.

A 12H for a bridge wait , EZ to hand pull.

A 20H for a rear (lead to the bow) overnight with usually a 35H in front. Fine in tidal areas.

A 60H is the storm anchor , seldom dug out and the 90H is Hurricane unit only used a couple of times in 50+ years.

The CQR 35 and 60 are for deep reversing tidal spots , where I'm too lazy to set the stern drop.

All Danforths are with 5 ft or so of chain the CQR with 20 ft.The rest is nylon.

I never set a snubber as the nylon does a fine job as its not monster thick.

As a start for overnight a pound of Danforth H per ft of boat seems to work.

A 3 story monster with an oxygen tent would need more , a sleek launch perhaps less.

Storm anchor would go a size up and a 20lb does great as a stern hook.

Remember you may be in the dink (or walking) carrying the anchor out to deep water , after a grounding .

Pity the chain rode fellows!

Storm surge and swell are two very different things. In the case of storm surge, one would be looking at depths and INCREASING scope to account for increased depth due to surge and increased wind.

In the case of Swell, how much swell would one expect in a typical storm in a somewhat protected anchorage 1-3 ft? You're simply not going to see 8-10 ft of swell. You would see 8-10 ft of surge and adjust scope accordingly.

The test called for the anchor to be set and then 100ft of rode to be retrieved. I don't see how that is a real world example of the impact of either surge or swell.

Shrew,

Thanks for your comments. My point was that decreasing scope and the resulting load on an anchor is not uncommon, and increasing scope to compensate during a storm surge is not always an option.

The initial plan for the Chesapeake Bay testing was to use the 81-ft Rachel Carson research vessel to pull the anchors at a pre-determined amount of scope through the soft mud, but it was quickly found that other than the 21 lb Fortress and 35 lb Danforth, the 44-46 lb fixed-fluke anchors offered minimal resistance.

Simply stated, the boat was too big, the bottom too soft, and most of the anchors too small to conduct controllable and repeatable tests.

And so we laid out a pre-determined amount of scope, then set the state-of-the-art Dynamic Positioning System aboard the Rachel Carson to keep the boat in place and pulled the anchors toward the boat.

In his detailed and lengthy follow-up test report, Bob Taylor noted that based upon the loads achieved during the testing that the decreasing scope had a minimal effect on the anchors' performance. His final summary paragraph:

"Although it is desirable to maintain a constant scope during a test, it seems that the test process employed at Chesapeake where scope was changed during the test had minimal affect on the test."

Shrew said:

Storm surge and swell are two very different things. In the case of storm surge, one would be looking at depths and INCREASING scope to account for increased depth due to surge and increased wind.

In the case of Swell, how much swell would one expect in a typical storm in a somewhat protected anchorage 1-3 ft? You're simply not going to see 8-10 ft of swell. You would see 8-10 ft of surge and adjust scope accordingly.

The test called for the anchor to be set and then 100ft of rode to be retrieved. I don't see how that is a real world example of the impact of either surge or swell.

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I have seen anchorages where 4 to 5 footers break over the bows of anchored vessels in a good blow.

My reference to surge was not storm surge but the action of the vessel trying to ride over waves while the bow is being pulled down by the ground tackle and forward into the waves from the overall give and take of cater nary and snubber stretch.

The vessels exposed to this type of action while sailing significantly back and forth put ground tackle to the test much more than just a blow.

True, protected anchorages are the ticket but not always available or the amount of wave action that wraps around a headland sometimes suprises.

"and increasing scope to compensate during a storm surge is not always an option."

Any weight lowered off the bow looped to the anchor line will usually be a great help of more scope is impossible.